For example, in sewing of a cuff portion and a bottom cuff portion of clothing, turn-back sewing is performed in which the edge part of the cloth is turned downward over a given width so as to be folded back under the remaining part of the cloth and then sewing of the vicinity of the edge is performed. When the turn-back sewing is to be performed by a common sewing machine, the edge of the cloth to be fed into the needle location position need be folded back with maintaining a fixed width by manual operation. This work causes a problem of requiring a great skill. In particular, when the cuff portion and the bottom cuff portion described above are to be processed, a cloth formed cylindrical in advance is to be processed. Thus, the work of folding back becomes more difficult and hence causes a possibility of poor sewing of diverse kind like a portion arises that the folding-back width is excessively small so that sewing of the edge is not achieved and, on the contrary, the folding-back width is excessively large so that the sewing line is formed at a position distant from the edge.
In view of such situations, in the conventional art, a sewing machine has been proposed that includes a turn-back guide device arranged in front of the needle location position (for example, see Japanese Patent Application Laid-Open No. H10-235054). The turn-back guide device includes: a guide plate overhanging, in parallel to a needle plate, a recess provided at a front position of the needle location position; a ruler member arranged in parallel to the upper face of the guide plate and bent at a position opposite to the tip part so as to be continuous to the bottom face of the recess; and an air ejection outlet opened at the bent part of the ruler member and ejecting air between the guide plate and the recess.
A cloth is supplied along the upper face of the guide plate in a state that the edge side is bent along the bending of the ruler member, and then fed in a direction along the tip edge of the guide plate. Air ejected from the air ejection outlet flows at a high speed between the lower face of the guide plate and the recess and biases the cloth overlapping with the lower face of the guide plate in a direction approximately perpendicular to the direction of feed so as to perform the operation of pressing the edge of the cloth against the deep inner side-end face of the recess.
By virtue of this, the cloth is folded up and down with the guide plate in between and the folding-back width on the edge side becomes a fixed width corresponding to the amount of overhang of the guide plate by virtue of the pressing against the end face of the recess. Thus, it is sufficient for the sewing worker to perform auxiliary work of, at a front position of the turn-back guide device, bending the edge side of the cloth over an appropriate width and then introducing it into a space between the ruler member and the recess. This permits reliable turn-back sewing over an appropriate width merely by causing a small labor load not requiring a skill.
Further, the turn-back guide device described in Japanese Patent Application Laid-Open No. H 10-235054 has a configuration that a nozzle ejecting air is arranged at a front position of the guide plate and the ruler plate so that even the turning of the edge side is automated by virtue of the ejected air from the nozzle and hence a labor load to the sewing worker is reduced further.